The automobile has various kinds of equipment, including the engine, to be controlled. Recently, most equipment for the automobile is of the electronically controlled type. Particularly, in the engine or similar parts, a control computer is used for concentrative control of the fuel injection system, carburetor or ignition.
A control apparatus for accessory equipment on a vehicle, other than the engine, provides different kinds of information for the driver. For example, information that the car speed exceeds a limited value, one or a plurality of head lamps are disconnected, or the engine key has been left inserted, is transmitted to the driver by means of sound or light, or the combination of both. The control apparatus has means for establishing a time period for the basis of a control in order to provide a pitch and intermittent period of sound and a flickering period of light. In addition, there are a clock, intermittent drive of wipers, and turn signal flickering which are directly controlled by this time period, thus requiring means for establishing the time period. Furthermore, there are car speed, engine temperature, or the combination of both which are employed to represent the operational state of the automobile, and in which, time is often used for the control element.
In the prior art, a control unit is produced for each accessory piece of equipment and a control circuit is provided for each function.
However, with the development of electronics, the number of accessories mounted on the vehicle has increased, and it has been desired to provide a single control unit with many functions which occupies less space and is compact.
In order for the driver to drive safely and comfortably, it is necessary that information by means of sound or light be correctly transmitted to the driver. Means for establishing time as the base of control has generally been through the use of frequency dividing circuits for properly dividing the frequency of the output signal from an oscillator. However, many different frequencies are required, and such frequency dividers are complicated and, thus, expensive. Particularly, in a conventional system in which a control device is used for each accessory, this drawback becomes prominent.
On the other hand, it is known to use a single computer for controlling a number of accessories; for example, see Japanese Patent Application Laid-Open No. 78535/1978 (Priority: French Patent application Nos. 76/32563 and 77/9285). However, the computer used in such a system is of the wired logic type which requires a frequency divider for each controlled object. Thus, such an apparatus is complicated and expensive.